近12000年以来北京地区地球磁场变化机理探讨

PRELIMINARY STUDY ON THE MECHANISM OF THE GEOMAGNETIC SECULAR VARIATIONS IN BEIJING OVER THE LAST 12000 YEARS

距今 1 2 0 0 0年以来北京地区地球磁场长期变化由长周期 (大于 1 0 0 0年 )和短周期(约 50 0年 )两部分组成 ,长周期和短周期分量分别受控于漂移场和稳定场的变化 .与日本地区相比 ,北京地区地球磁场最显著的特征是在距今 ( 51 1 0— 4670 )± 1 1 0年之间曾发生短极性漂移事件 ,这样的短极性地磁事件可能与地球外核流体运动的异常变化有关 .

The paleomagnetic secular variation (PSV) in Beijing over the last 12000 years can be divided into long term (>1000 years) and short term (500\_1000 years) components. The long term variations are mainly controlled by changes in the drifting field, while the short term variations are most probably caused by the fluctuation of the standing field. Comparing to the PSV in Japan, a remarkable feature in Beijing is a short geomagnetic excursion occurring between (5110\_4670)±110 years,which might be related with the anomaly movement of the fluid in the Earth's outer core.